Journal of Analytical and Applied Pyrolysis 91 (2011) 205–209 Contents lists available at ScienceDirect Journal of Analytical and Applied Pyrolysis journal homepage: www.elsevier.com/locate/jaap Sulphur capturing by an inertinite rich high ash bituminous coal during conversion in a pilot packed bed reactor M. Pat Skhonde a,b , Christien A. Strydom b,∗ , John R. Bunt a,b , Harold H. Schobert b,c a Sasol Technology R&D, 1 Klasie Havenga Avenue, PO Box 1, Sasolburg 1947, South Africa b Chemical Resource Beneficiation, North-West University, Potchefstroom Campus, Private Bag X6001, Potchefstroom 2520, South Africa c Department of Energy & Mineral Engineering, Pennsylvania State University, 204 Res. East, University Park, PA 16802-5000, USA article info Article history: Received 6 September 2010 Accepted 16 February 2011 Available online 23 February 2011 Keywords: Sulphur capturing Pilot packed bed reactor CaS FeS abstract Sulphur is liberated from the coal structure and released in various forms during coal thermal processing. The possibility of sulphur capture, through injection of SO 2 into a packed coal bed in a pilot packed bed reactor operated under controlled conditions, was investigated. Results showed that SO 2 injection into a packed coal bed leads to sulphur capturing mainly in the coal mineral matter. Mineralogical analysis (XRD) of the ash samples obtained from the experiments indicates that the sulphur-capture products that are formed include FeS, CaS and small amounts of organically associated sulphur. Troilite (FeS) was observed in the SO 2 treated samples, while no troilite was observed in the reference samples. Calcite and dolomite are transformed into CaO and other calcium-containing compounds in the pyrolyses zone, with some CaS being formed in the gasification zone via the reaction between SO 2 and CaO in the presence of CO from the gasification reactions. CaO formed at the high temperatures in the combustion and ash zone is transformed into CaSO 4 upon reaction with SO 2 as an oxidizing atmosphere prevails in this zone. The existence of these compounds is dependent on the extent of oxidising or reducing conditions during the process, with CaS favoured under reducing conditions and CaSO 4 favoured under oxidising conditions. © 2011 Elsevier B.V. All rights reserved. 1. Introduction Sulphur emission from especially coal combustion processing plants is one of the environmental concerns that limit the growth of coal utilisation worldwide. During coal combustion processes, sulphur is liberated from the coal structure and released mainly as SO 2 and SO 3 , whereas, during coal gasification processes, sul- phur is liberated from the coal structure and released as H 2 S and COS [1,2]. Usually these gases are removed down-stream via var- ious processes as part of gas purification steps. In situ sulphur capturing is one of the possible further means to reduce sulphur emissions. Calcium based sorbents such as limestone and dolomite have been used to provide the necessary calcium to react with sul- phur leading to capturing of sulphur by the minerals. The use of calcium based sorbents for flue gases and fuel gas desulphurisa- tion has been researched and reported on by various authors [3–5]. These authors’ work on sulphur capturing is limited to the use of calcium-based sorbents for flue gases and fuel gases desulphurisa- tion for fine coal combustion applications. There is limited in situ sulphur capturing reported in literature where lump coal is used. ∗ Corresponding author. Tel.: +27 182992340; fax: +27 182992350. E-mail address: christien.strydom@nwu.ac.za (C.A. Strydom). The possibility of capturing sulphur in situ through injection of the SO 2 into a packed coarse coal bed under controlled conditions in a pilot packed bed reactor was investigated. The objective of this study was to utilise the high-temperature transformation products of limestone and dolomite in the coal for in situ capturing of injected sulphur in a batch coal bed. 2. Experimental methods 2.1. Sample preparation The experimental procedures were conducted using an iner- tinite rich, medium rank, high ash bituminous coal blend, from a Highveld colliery in South Africa, with proximate and ultimate analysis properties indicated in Table 1. Bunt et al. [6] performed extensive petrographic analysis on this raw coal and described the inertinite rich nature of the coal. The coal was prepared by screening and sizing according to the particle size distribution and masses. The fractions between -1.70 and +75 mm were all mixed and homogenised before being loaded into the pilot packed bed reactor. The total mass loaded was 240 kg. The results from the XRD analysis of the coal are summarized in Table 2. 0165-2370/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.jaap.2011.02.008